1 files changed, 35 insertions, 0 deletions
diff --git a/hurd/interface/fsys/04.mdwn b/hurd/interface/fsys/04.mdwn
index 0ef242f9..60d314c5 100644
--- a/hurd/interface/fsys/04.mdwn
+++ b/hurd/interface/fsys/04.mdwn
@@ -18,3 +18,38 @@ License|/fdl]]."]]"""]]
 
 Sync a filesystem.  Args are the same as for [[`file_syncfs`|file_syncfs]] in
 [[`fs.defs`|fs]].
+
+# Implementation Examples
+
+Servers that either don't keep any unsynchronized state (or don't have a
+backing store at all) can simply `return 0`.  Examples: [[translator/symlink]],
+[[translator/nfs]].
+
+## [[libtrivfs]]
+
+Invoke [[`file_sync`|file_sync]] on the underlying node.  Rationale: the
+underlying node represents this filesystem's backend, and once this node is
+synchronized, the whole [[libtrivfs]]-based filesystem is to be considered
+synchronized.
+
+### [[storeio]] / [[streamio]]
+
+Instead of to the underlying node, pass the call through to the backend
+(device).
+
+## [[libnetfs]]
+
+Invoke `netfs_attempt_syncfs`.
+
+## [[libdiskfs]]
+
+Invoke [[`fsys_syncfs`|fsys_syncfs]] on all active children, and invoke
+`diskfs_sync_everything` and `diskfs_set_hypermetadata`.
+
+# Usage Examples
+
+## [[libdiskfs]]
+
+In the implementations of both [[`file_syncfs`|file_syncfs]] and
+[[`fsys_syncfs`|fsys_syncfs]], [[`fsys_syncfs`|fsys_syncfs]] is invoked on all
+active children.